Association Between Pediatric Traumatic Brain Injury and Epilepsy at Later Ages in Finland – a Nationwide Register‐based Cohort Study

Abstract Objective To examine how pediatric traumatic brain injury (pTBI) correlated with incidence of epilepsy at later ages in Finland. Methods A nationwide retrospective register‐based cohort study from 1998 to 2018. The study group consisted of 71 969 pediatric (<18 years) patients hospitalized with TBI and a control group consisting of 64 856 pediatric patients with distal extremity fracture. Epilepsy diagnoses were gathered from the Finnish Social Insurance Institution. Kaplan‐Meier (KM) and multivariable Cox regression models were conducted to analyze the probability of epilepsy with 95% confidence intervals (CI). Results Cumulative incidence rates (CIR) for the first 2 years were 0.5% in the pTBI group and 0.1% in the control group. The corresponding rates after 15 years of follow‐up were 1.5% in the pTBI group and 0.7% in the control group. Due to proportional hazard (PH) violations, the study population was split to the first 2 years and in subgroup analysis 4 years. During the first 2 years of surveillance, the hazard ratio (HR) for the pTBI group was 4.38 (CI: 3.39‐5.66). However, between years 2 and 20, the HR for the pTBI group was 2.02 (CI: 1.71‐2.38). A total of 337 patients (0.47%) underwent neurosurgery and 36 (10.7%) patients subsequently developed epilepsy. The CIR for the first year after TBI were 4.5% (CI: 2.3‐6.7%) in operatively managed patients and 0.3% (CI: 0.3‐0.4%) in non‐operatively managed patients. Corresponding figures after 15 years were 12.0% (CI: 8.2‐15.8%) and 1.5% (CI: 1.4‐1.6%). During the first 4 years of surveillance, the HR for the operative pTBI group was 14.37 (CI: 9.29‐20.80) and 3.67 (CI: 1.63‐8.22) between years 4 and 20. Significance pTBI exposes patients to a higher risk for posttraumatic epilepsy (PTE) for many years after initial trauma. Children who undergo operative management for TBI have a high risk for epilepsy, and this risk was highest during the first 4 years after injury.